YBX3 regulates thermogenesis and energy expenditure by regulating UCP1 in brown adipose tissue
Objective To observe the effects and mechanisms of Y-box protein 3(YBX3)deletion in brown adipose tissue(BAT)on thermogenesis and energy consumption in mice.Methods The mice were placed in a 4℃ environ-ment as a cold stimulation method.Lentiviral infection assay was used to construct a human stromal vascular fraction cell line that overexpresses YBX3 or inhibits YBX3 expression.Oxygen consumption rate was used to assess mitochon-drial function.Mouse BAT was injected with YBX3 siRNA(si-Ybx3)to inhibit YBX3 expression in BAT.The oxygen consumption rate,CO2 release rate and energy consumption rate of mice were detected to evaluate the energy metabo-lism of mice.qRT-PCR,Western blotting,and immunofluorescence staining assays were used to detect peroxisome pro-liferator-activated receptor gamma coactivator 1α(PGC-1α),uncoupling protein 1(UCP1)and YBX3 expression.HE staining was used to detect the size of lipid droplets of adipocytes in BAT.RNA-binding protein immunoprecipitation was used to extract the mRNA bindsing specifically to YBX3.Next-generation sequencing assay was used to identify mRNA.Dual-luciferase reporter gene systems were used to detect the binding of YBX3 to the target sequence.Results YBX3expression in BAT of wild-type mice was induced by cold stimulation(P<0.05).Overexpressing YBX3 promoted the expression of the thermogenic gene PGC-1α and UCP1 after human stromal vascular fraction cell line cells being induced into mature brown adipocytes(P<0.05).Silencing YBX3 in human stromal vascular fraction cell line cells inhibited the expression of PGC-1α and UCP1(P<0.05)and mitochondrial oxidative phosphorylation after being induced into mature brown adipocytes(P<0.05).Compared with the control group,mice injected with si-Ybx3 had signif-icantly lower energy consumption(P<0.05),lower body temperature in a cold environment(P<0.05),and lower ex-pression levels of thermogenic genes(P<0.05).The size of lipid droplets in adipocytes increased significantly(P<0.05).Compared with at 25℃,the expression of YBX3 in the nucleus of brown adipocytes significantly increased from mice kept at 4℃(P<0.05).YBX3 specifically bound to the target sequence in the 3'untranslated region of PGC-1α mRNA(P<0.05).YBX3 specifically bound to PGC-1α and UCP1 promoter regions(P<0.05).Conclusion YBX3 in BAT can affect thermogenesis and energy metabolism by regulating the expressions of PGC-1α and UCP1.
Y-box binding protein 3ThermogenesisEnergy expenditureBrown adipose tissueUncoupling protein 1
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